Expiratory Pressure Relief (EPR)

Definition - What does Expiratory Pressure Relief (EPR) mean?

Expiratory pressure relief is a trademarked feature of ResMed brand positive airway pressure machines and other sleep therapy devices. Other manufacturers of devices used to treat sleep apnea offer similar features under different trade names.

In all instances, these mechanisms are designed to lower the air pressure delivered through the positive airway pressure device when the wearer exhales. This relief of pressure makes it easier for the wearer to exhale as their expiration is not being met by the full force of the device's incoming air pressure.

When describing this feature of sleep apnea devices in generic terms, the phrase "pressure-relief feature" is used. Other trade names for this feature include C-Flex, AirSense, Prisma and SoftPAP.

WorkplaceTesting explains Expiratory Pressure Relief (EPR)

Positive airway pressure devices treat sleep apnea by delivering a positive flow of air into the air passages of the wearer of the device. This delivery is achieved through the use of a mask that may partially or fully cover the individual's nose and/or mouth. The positive air pressure delivered by these machines helps to prop open weakened air passages, preventing the temporary breathing stoppages characteristic of obstructive sleep apnea. Air pressure delivered by these devices may be pre-set in the case of a continuous positive airway pressure device (CPAP) or adjust in response to the individual's breathing patterns in the case of an auto-titrating positive airway pressure device (APAP).

Because these devices are worn continually while a person sleeps, it affects both their ability to inhale and exhale. Some wearers, particularly those who require high settings, experience discomfort or difficulty exhaling against the positive air pressure that the device delivers. The pressure-relief feature is designed to alleviate that difficulty.